[FPGA开发] 【Altera SoC体验之旅】多串口服务器之串口模块设计（1）

chenzhufly 2015-6-1 00:50 楼主

作者：chenzhufly QQ：36886052

1、硬件环境

硬件平台：Embest SoC --LarkBoard

软件平台：开发板-linux-3.10.31

Quartus 14.0

2、代码结构

我不生产代码，我只是代码的搬运工，代码来源于网络，分享与网络。但还是需要做一些修改才能使用，慢慢来吧，结构还是不错的，我们一起学习学习。

主要有三个文件uart_top.v，uart_xmit. v，uart_rcv. v，结构如下：

1）uart_top.v是串口逻辑模块的顶层文件，负责管理串口的发送和接收

2）uart_xmit. v为串口的发送模块

3）uart_rcv. v位串口的接收模块

3、代码分析

1）uart_top.v

可以清楚的看到在，在接收模块和发送模块的前端都加了fifo模块，深度为256个字节。

`timescale 1 ns / 10 ps
`define BAUD_DIV 6875
module uart_top
(
// Global signal definition
input rst ,
input sys_clk ,
input pci_clk ,
input pci_wren ,
input [7:0] pci_wrdat ,
input pci_rden ,
output [7:0] pci_rddat ,
// Local bus register
input SEND_CMD ,
input RCV_EN ,
output RCV_IRQ ,
input PARITY_BIT_EN ,
input PARITY_SEL ,
output PARITY_ERROR ,
//output uart_ok ,
output xmit_busy ,
output xmit_ok ,
output xmit_fifo_empty ,
output rcv_fifo_empty ,
// Uart interface
input rxd ,
output txd
);
wire xmit_fifo_rden;
wire [7:0] xmit_fifo_rddat;
wire rcv_fifo_wren;
wire [7:0] rcv_fifo_wrdat;
//wire rcv_fifo_empty;
/*---------------------------------------------------------------------
-- transmit module instantiation
----------------------------------------------------------------------*/
T_FIFO_256x8 xmit_fifo_256x8
(
.din (pci_wrdat ),
.rd_clk (sys_clk ),
.rd_en (xmit_fifo_rden ),
.rst (1'b0 ),
.wr_clk (pci_clk ),
.wr_en (pci_wren ),
.almost_empty ( ),
.almost_full ( ),
.dout (xmit_fifo_rddat),
.empty (xmit_fifo_empty),
.full ( )
);
uart_xmit uart_xmit_inst
(
.sys_clk (sys_clk ),
.rst (rst ),
// PCI command interface
.SEND_CMD (SEND_CMD ),
.PARITY_BIT_EN (PARITY_BIT_EN ), // parity bit enable or not, 1 = enable, 0 = disable;
.PARITY_SEL (PARITY_SEL ), // determine ODD/EVEN parity, 1 = ODD, 1 = EVEN;
// UART command data fifofer interface
.fifo_rden (xmit_fifo_rden ),
.fifo_rddat (xmit_fifo_rddat),
.fifo_empty (xmit_fifo_empty),
// UART status interface
.uart_busy (xmit_busy ),
.uart_ok (xmit_ok ),
// UART interface
.txd (txd )
);
/*---------------------------------------------------------------------
-- receive module instantiation
----------------------------------------------------------------------*/
T_FIFO_256x8 rcv_fifo_256x8
(
.din (rcv_fifo_wrdat ),
.rd_clk (sys_clk ),
.rd_en (pci_rden ),
.rst (1'b0 ),
.wr_clk (sys_clk ),
.wr_en (rcv_fifo_wren ),
.almost_empty ( ),
.almost_full ( ),
.dout (pci_rddat ),
.empty (rcv_fifo_empty ),
.full ( )
);
uart_rcv uart_rcv_inst
(
.sys_clk (sys_clk ),
.rst (rst ),
// PCI command interface
.RCV_EN (RCV_EN ),
.RCV_IRQ (RCV_IRQ ),
.PARITY_BIT_EN (PARITY_BIT_EN ), // parity bit enable or not, 1 = enable, 0 = disable;
.PARITY_SEL (PARITY_SEL ), // determine ODD/EVEN parity, 1 = ODD, 1 = EVEN;
.PARITY_ERROR (PARITY_ERROR ),
// UART command data fifofer interface
.fifo_wren (rcv_fifo_wren ),
.fifo_wrdat (rcv_fifo_wrdat ),
.fifo_empty (rcv_fifo_empty ),
// UART interface, which should be registered before internal access
.rxd (rxd )
);
endmodule

2）uart_xmit. v

串口发送协议的解析和处理

`timescale 1 ns / 10 ps
`define BAUD_DIV 6875
module uart_xmit
(
input sys_clk ,
input rst ,
// PCI command interface
input SEND_CMD ,
input PARITY_BIT_EN , // parity bit enable or not, 1 = enable, 0 = disable;
input PARITY_SEL , // determine ODD/EVEN parity, 1 = ODD, 1 = EVEN;
// UART command data fifofer interface
output reg fifo_rden ,
input [7:0] fifo_rddat ,
input fifo_empty ,
// UART status interface
output reg uart_busy ,
output reg uart_ok ,
// UART interface
output reg txd
);
parameter frame_idle = 3'b000, frame_putchar = 3'b001, frame_bit_call = 3'b010, frame_done = 3'b011;
parameter bit_idle = 3'b000, bit_start = 3'b001, bit_xmit = 3'b010, bit_parity = 3'b011, bit_stop = 3'b100;
reg [2:0] cur_frame;
reg [2:0] next_frame;
reg [2:0] cur_bit;
reg [2:0] next_bit;
reg [7:0] xmit_char;
reg xmit_start;
reg xmit_done;
reg [3:0] bit_cnt;
reg bit_over;
reg [15:0] baud_cnt;
reg shift_en;
/*---------------------------------------------------------------------
-- uart byte frame state control state machine
----------------------------------------------------------------------*/
always [url=home.php?mod=space&uid=496176]@[/url] ( * )
begin
case ( cur_frame )
frame_idle:
if ( SEND_CMD == 1'b1 ) // put frame char when pci send command event detected
//if ( fifo_empty == 1'b0 )
next_frame <= frame_putchar;
else
next_frame <= frame_idle;
frame_putchar:
//if ( char_over == 1'b1 )
if ( fifo_empty == 1'b1 )
next_frame <= frame_done;
else
next_frame <= frame_bit_call;
frame_bit_call:
if ( xmit_done == 1'b0 )
next_frame <= frame_bit_call;
else if ( fifo_empty == 1'b1 )
next_frame <= frame_idle;
else
next_frame <= frame_putchar;
//if ( xmit_done == 1'b1 )
// next_frame <= frame_putchar;
//else
// next_frame <= frame_bit_call;
frame_done:
next_frame <= frame_idle;
default:
next_frame <= frame_idle;
endcase
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
cur_frame <= frame_idle;
else
cur_frame <= next_frame;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
xmit_start <= 1'b0;
else
if ( cur_frame == frame_putchar )
xmit_start <= 1'b1;
else
xmit_start <= 1'b0;
end
/*---------------------------------------------------------------------
-- uart byte frame state control state machine
----------------------------------------------------------------------*/
always @ ( * )
begin
case ( cur_bit )
bit_idle:
if ( xmit_start == 1'b1 )
next_bit <= bit_start;
else
next_bit <= bit_idle;
bit_start:
if ( shift_en == 1'b1 )
next_bit <= bit_xmit;
else
next_bit <= bit_start;
bit_xmit:
if ( bit_over == 1'b0 )
next_bit <= bit_xmit;
else if ( PARITY_BIT_EN == 1'b1 )
next_bit <= bit_parity;
else
next_bit <= bit_stop;
bit_parity:
if ( shift_en == 1'b0 )
next_bit <= bit_parity;
else
next_bit <= bit_stop;
bit_stop:
if ( shift_en == 1'b1 )
next_bit <= bit_idle;
else
next_bit <= bit_stop;
default:
next_bit <= bit_idle;
endcase
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
cur_bit <= bit_idle;
else
cur_bit <= next_bit;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
xmit_done <= 1'b0;
else
if ( cur_bit == bit_stop && shift_en == 1'b1 )
xmit_done <= 1'b1;
else
xmit_done <= 1'b0;
end
/*---------------------------------------------------------------------
-- bit counter control
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
bit_cnt <= 4'h0;
else
if ( cur_bit == bit_idle )
bit_cnt <= 4'h0;
else if ( shift_en == 1'b1 )
bit_cnt <= bit_cnt + 1'b1;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
bit_over <= 1'b0;
else
if ( cur_bit == bit_idle )
bit_over <= 1'b0;
else if ( bit_cnt == 4'h9 )
bit_over <= 1'b1;
end
/*---------------------------------------------------------------------
-- baud rate control
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
baud_cnt <= 16'b0_0000_0000;
else
if ( cur_bit == bit_idle || baud_cnt == `BAUD_DIV )
baud_cnt <= 16'b0_0000_0000;
else
baud_cnt <= baud_cnt + 1'b1;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
shift_en <= 1'b0;
else
if ( baud_cnt == `BAUD_DIV )
shift_en <= 1'b1;
else
shift_en <= 1'b0;
end
/*---------------------------------------------------------------------
-- UART fifo interface
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
fifo_rden <= 1'b0;
else
fifo_rden <= xmit_start;
end
/*---------------------------------------------------------------------
-- TXD controll logic
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
xmit_char <= 8'h00;
else
if ( cur_bit == bit_start )
xmit_char <= fifo_rddat;
else if ( cur_bit == bit_xmit && shift_en == 1'b1 )
// xmit_char <= { xmit_char[6:0], xmit_char[7] };
xmit_char <= { xmit_char[0], xmit_char[7:1] };
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
txd <= 1'b1;
else if ( shift_en == 1'b1 )
case ( cur_bit )
bit_start :
txd <= 1'b0;
bit_xmit:
// txd <= xmit_char[7];
txd <= xmit_char[0];
bit_parity:
txd <= ( xmit_char[7] ^ xmit_char[6] ^ xmit_char[5] ^ xmit_char[4] ^
xmit_char[3] ^ xmit_char[2] ^ xmit_char[1] ^ xmit_char[0] ) ^ (~PARITY_SEL);
default:
txd <= 1'b1;
endcase
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
uart_ok <= 1'b0;
else
if ( SEND_CMD == 1'b1 )
uart_ok <= 1'b0;
else if ( fifo_empty == 1'b1 && xmit_done == 1'b1 )
uart_ok <= 1'b1;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
uart_busy <= 1'b0;
else
if ( cur_frame == frame_idle )
uart_busy <= 1'b0;
else if ( fifo_empty == 1'b0 )
uart_busy <= 1'b1;
end
endmodule

3）uart_rcv. v

串口接收协议的解析和处理

`timescale 1 ns / 10 ps
`define BAUD_DIV 6875
module uart_rcv
(
input sys_clk ,
input rst ,
// PCI command interface
input RCV_EN ,
output RCV_IRQ ,
input PARITY_BIT_EN , // parity bit enable or not, 1 = enable, 0 = disable;
input PARITY_SEL , // determine ODD/EVEN parity, 1 = ODD, 1 = EVEN;
output reg PARITY_ERROR ,
// UART command data fifofer interface
output reg fifo_wren ,
output reg [7:0] fifo_wrdat ,
input fifo_empty ,
// UART interface, which should be registered before internal access
input rxd
);
reg rxd_reg;
reg rxd_reg_sft;
reg [7:0] rxd_s0_cnt;
reg [7:0] rxd_s1_cnt;
reg rxd_anti_glitch;
reg [2:0] cur_bit;
reg [2:0] next_bit;
reg [7:0] rcv_char;
reg start_event;
reg start_event_dly;
reg [3:0] bit_cnt;
reg bit_over;
reg [15:0] baud_cnt;
reg shift_en;
reg sample_en;
parameter bit_idle = 3'b000, bit_start = 3'b001, bit_rcv = 3'b010, bit_parity = 3'b011, bit_stop = 3'b100;
/*---------------------------------------------------------------------
-- rxd anti-glitch control
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
rxd_s0_cnt <= 0;
else
if ( rxd == 1'b1 )
rxd_s0_cnt <= 0;
else if ( rxd_s0_cnt[4] == 1'b0 )
rxd_s0_cnt <= rxd_s0_cnt + 1'b1;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
rxd_s1_cnt <= 0;
else
if ( rxd == 1'b0 )
rxd_s1_cnt <= 0;
else if ( rxd_s1_cnt[4] == 1'b0 )
rxd_s1_cnt <= rxd_s1_cnt + 1'b1;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
rxd_anti_glitch <= 1'b1;
else
if ( rxd_s0_cnt[4] == 1'b1 )
rxd_anti_glitch <= 1'b0;
else if ( rxd_s1_cnt[4] == 1'b1 )
rxd_anti_glitch <= 1'b1;
end
/*---------------------------------------------------------------------
-- start bit detection
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
begin
rxd_reg <= 1'b1;
rxd_reg_sft <= 1'b1;
end
else
begin
rxd_reg <= rxd_anti_glitch;
rxd_reg_sft <= rxd_reg;
end
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
start_event <= 1'b0;
else
if ( rxd_reg == 1'b0 && rxd_reg_sft == 1'b1 &&
( cur_bit == bit_idle || cur_bit == bit_stop ) )
start_event <= 1'b1;
else
start_event <= 1'b0;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
start_event_dly <= 1'b0;
else
start_event_dly <= start_event;
end
/*---------------------------------------------------------------------
-- uart byte frame state control state machine
----------------------------------------------------------------------*/
always @ ( * )
begin
case ( cur_bit )
bit_idle:
if ( start_event == 1'b1 )
next_bit <= bit_start;
else
next_bit <= bit_idle;
bit_start:
if ( shift_en == 1'b1 )
next_bit <= bit_rcv;
else
next_bit <= bit_start;
bit_rcv:
if ( bit_over == 1'b0 )
next_bit <= bit_rcv;
else if ( PARITY_BIT_EN == 1'b1 )
next_bit <= bit_parity;
else
next_bit <= bit_stop;
bit_parity:
if ( shift_en == 1'b0 )
next_bit <= bit_parity;
else
next_bit <= bit_stop;
bit_stop:
//if ( shift_en == 1'b1 )
// next_bit <= bit_idle;
//else
// next_bit <= bit_stop;
if ( start_event == 1'b1 ) // Caution!!! start_event will occur in bit_stop phase
next_bit <= bit_start;
else if ( shift_en == 1'b1 )
next_bit <= bit_idle;
else
next_bit <= bit_stop;
default:
next_bit <= bit_idle;
endcase
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
cur_bit <= bit_idle;
else
cur_bit <= next_bit;
end
/*---------------------------------------------------------------------
-- bit counter control
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
bit_cnt <= 4'h0;
else
if ( cur_bit == bit_idle || ( cur_bit == bit_stop && start_event == 1'b1 ) )
bit_cnt <= 4'h0;
//else if ( shift_en == 1'b1 )
else if ( shift_en == 1'b1 && start_event_dly == 1'b0 ) // modified by andrew, 2007-5-24 11:46
bit_cnt <= bit_cnt + 1'b1;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
bit_over <= 1'b0;
else
if ( cur_bit == bit_idle || ( cur_bit == bit_stop && start_event == 1'b1 ) )
bit_over <= 1'b0;
else if ( bit_cnt == 4'h9 )
bit_over <= 1'b1;
end
/*---------------------------------------------------------------------
-- baud rate control
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
baud_cnt <= 9'b0_0000_0000;
else
//if ( cur_bit == bit_idle || baud_cnt == `BAUD_DIV )
if ( cur_bit == bit_idle ||
( cur_bit == bit_stop && start_event == 1'b1 ) ||
baud_cnt == `BAUD_DIV ) // to avoid error to be accumulated!!!!!
baud_cnt <= 9'b0_0000_0000;
else
baud_cnt <= baud_cnt + 1'b1;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
shift_en <= 1'b0;
else
if ( baud_cnt == `BAUD_DIV )
shift_en <= 1'b1;
else
shift_en <= 1'b0;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
sample_en <= 1'b0;
else
if ( baud_cnt == (`BAUD_DIV >> 1) )
sample_en <= 1'b1;
else
sample_en <= 1'b0;
end
/*---------------------------------------------------------------------
-- Character received from uart interface
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
rcv_char <= 8'h00;
else
if ( cur_bit == bit_rcv && sample_en == 1'b1 )
//rcv_char <= { rcv_char[6:0], rxd_reg };
rcv_char <= { rxd_reg, rcv_char[7:1] };
end
/*
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
PARITY_ERROR <= 1'b0;
else
if ( cur_bit == bit_parity && shift_en == 1'b1 )
PARITY_ERROR <= ( rxd_reg == ( getchar[7] ^ getchar[6] ^ getchar[5] ^ getchar[4] ^
getchar[3] ^ getchar[2] ^ getchar[1] ^ getchar[0] ) ^ (~PARITY_SEL)
) ? 1'b0 : 1'b1;
end
*/
/*---------------------------------------------------------------------
-- FIFO control logic
----------------------------------------------------------------------*/
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
fifo_wren <= 1'b0;
else
if ( cur_bit == bit_stop && ( shift_en == 1'b1 || start_event == 1'b1 ) )
fifo_wren <= 1'b1;
else
fifo_wren <= 1'b0;
end
always @ ( negedge rst or posedge sys_clk )
begin
if ( rst == 1'b0 )
fifo_wrdat <= 0;
else
fifo_wrdat <= rcv_char;
end
assign RCV_IRQ = ~fifo_empty;
endmodule